1. Field of the Invention
The present invention relates to an automated sewing device for automatically sewing together two juxtaposed end portions respective of two different base materials of different shapes each of which has been cut formed in a predetermined shape.
2. Description of Prior Art
The automated sewing device of the afore-stated kind is known in the art, and in particular, various kinds of automated sewing devices have been disclosed, which are capable of automatically sewing a curved end of one material with a rectilinear or uneven end of another material, or vice versus. Typical examples of such sewing devices are known from the Japanese Laid-Open Utility Model Publication No. 54-72966, the Japanese Patent No. 2691737, and the Japanese Laid-Open Patent Publication No. 7-194870.
According to those known automated sewing devices, one curved end portion of first material is automatically guided in a fixed direction to a sewing needle through automatically controlled movement of a guide plate on which the first material is secured, while another straight or uneven end portion of second material is also automatically guided in a proper direction so as to be in alignment with that one curved end portion of first material. In this way, a fixed margin to seam is attained constant in both of those first and second materials, so that both end portions of the first and second materials are neatly aligned with each other and sewn together, with a seam extending precisely along the thus-sewn two end portions.
In the case of forming a seat cover for use on automotive or vehicle seat, the so-called “trim cover assembly” having a certain multi-layered structure is formed in most instances. Typically, a material for forming such trim cover assembly for automotive seat is of a three-layer lamination structure comprising a top cover layer, a foam wadding layer, and a wadding cover layer in this order (see FIGS. 8 (A) and 8 (B)). Hence, this sort of material is relatively large in thickness. In practical assembly of seat cover materials, a plurality of such three-layered thick materials are stacked on top of each other in layers and then trimmed all at once into a given shape, with the result that some of so trimmed materials become irregular in their respective contours and causes some portions that are not made to measure.
In this connection, the above-noted conventional automated sewing devices operate to sew together the materials with a fixed seam allowance. If the foregoing irregular sizes of materials are sew together by that automated sewing device, a resulting sewn product inevitably has some portions irregular in size. That is, if the materials that have been cut or trimmed into a size larger than a predetermined size as stated above are sewn together with a fixed seam allowance by the known automated sewing device, a resulting sewn product inevitably has some large portions exceeding the predetermined size. Or, if the materials that have been cut or trimmed into a size smaller than a predetermined size are likewise automatically sewn together with a fixed seam allowance, a resulting sewn product inevitably has some portions smaller than the predetermined size.